1. Technical Field
The present invention relates to a camera module, and more particularly, to a camera module capable of being mounted at a portable terminal so as to photograph an image.
2. Description of the Related Art
In accordance with the recent development of a technology of a portable terminal such as a cellular phone, a personal digital assistant (PDA), a tablet personal computer (PC), and the like, the portable terminal has been used as multi-convergence such as a music, a movie, a television, a game, and the like, as well as a simple phone function. The most typical product among products leading the development to the multi-convergence may be a camera module. The camera module has been changed for implementation of various additional functions such as auto focusing AF and optical zoom simultaneously with changing based on high pixel.
The portable terminal as mentioned above tends to be miniaturized, slimed, and multi-functionalized according to preference of an element. In addition, as the camera module which is mounted at the portable terminal has also been gradually developed, a size of the camera module has decreased, and pixels and functions thereof have increased. Therefore, technologies for precisely manufacturing components which are mounted inside the camera module are also required for improving image performance and reference for evaluating thereof gradually become complicated.
In general, the camera module includes a substrate on which an image sensor is mounted, a housing which is closely bonded onto the substrate, and a lens barrel which is mounted on the housing, and matches an optical axis of a lens which is stacked and bonded in the lens barrel to an optical axis of the image sensor which is mounted on the substrate to allow an accurate image to be photographed.
However, when the camera module is assembled using many optical components including the image sensor, the optical axis between the image sensor and the lens may be distorted due to a tolerance by each part, an assembly tolerance or the like, that is, a tilt may be generated, such that resolution defects may occur in final products.
In this case, at the time of evaluating the image of the lens barrel which is mounted on the camera module among a plurality of optical components, a bottom surface of a press-fitting ring fixing the lens after stack-bonding the lens is used as an image evaluating reference surface of the lens barrel, wherein the bottom surface of the press-fitting ring has low flatness due to an accumulated error of a stack assembly which is generated at the time of bonding the lens, and a difference occurs in perpendicularity between measurements of the bottom surface of the lens barrel and a side of the module at the time of actually assembling the module, to cause a high defect ratio of the lens barrel at the time of evaluating lens performance and degrade the resolution.